Numerous processes have been devised for converting certain nitrogen compounds to nitric oxide (NO). Representative of such processes is that disclosed in U.S. Letters Pat. No. 3,919,397 to R. K. Gould in which a gas is passed through a plurality of alumina tubes containing wires of a catalytic material, such as, platinum. The wires are connected to a source of electrical energy for resistively heating the wire in order to speed up the thermal conversion of nitrogen to nitric oxide when passed into contact with the wires. In this and other processes, it is known also that one can detect or measure the concentration of nitric oxide by combining ozone with the nitric oxide to produce nitrogen dioxide (NO.sub.2) in an excited electronic state, oxygen and subsequently emitted light. The quantity of light produced is a measurement of the concentration or amount of nitric oxide present and typically is carried out by various types of chemiluminescent detectors. Gould, however, suggests that materials, such as gold, which he asserts are consumed in the reaction with NO.sub.2 to produce NO are not properly catalysts. Gould fails to recognize the potential of utilizing gold as a catalyst in redox reaction processes in which certain reducing agents when combined with oxides of nitrogen are capable of being converted to more valuable materials.
Numerous other patents and publications may be found in the literature which disclose a variety of approaches to so-called NO.sub.x converters as well as the use of gas or liquid chromatography and chemiluminescence detectors for measuring resultant products of the reaction. Representative patents are U.S. Letters Pat. Nos. 4,301,114 to D. P. Rounbehler et al, 4,066,409 to D. H. Fine, 3,963,928 and 3,882,028 to W. J. Zolner, and 4,193,963 to W. Bruening et al. Rounbehler et al, for example, is concerned more with a particular form of molecular sieve for trapping species other than NO and NO.sub.2 that could interfere with the detection process; and in Fine, organic nitrogen-containing compounds are chromatographically separated, pyrolyzed in contact with oxygen and the nitric oxide emitted from the decomposition is measured.
Other patents pertain to methods and means for catalytic reduction of oxides of nitrogen. For example, U.S. Letters Pat. No. 4,162,235 to G. J. K. Acres et al is directed to a catalytic purification process for exhaust gas in which platinum group metals including gold are associated with one or more base metals to carry out catalytic reduction of oxides of nitrogen in the presence of suitable reducing agents. In U.S. Letters Pat. No. 4,028,274 to H. R. Kunz, various metal catalysts are proposed for use in combination with a support material, such as, a carbon powder and broadly suggests the utilization of gold as a catalyst but not in any specific reaction or pro- cess.
To the best of our knowledge, no one has recognized the ability to carry out a redox reaction, i.e. a reduction oxidation process in which oxides of nitrogen are combined with a reducing agent, such as, alcohols, olefins, aldehydes or other selected organic compounds which can be catalyzed by a heated gold surface to convert the organic compounds selected to new, more valuable, oxidized or dehydrogenated species. A related feature of the present invention resides in the ability to selectively detect the new species by a combination of gas chromatography and chemiluminescent measurement without detecting the presence of other compounds, such as, alkanes, chlorinated hydrocarbons, water, oxygen and nitrogen. Since oxygenated organic compounds typically exist at trace levels in the atmosphere while the alkanes are present at much higher concentrations, this selective process is useful in improving the detection of the oxygenated constituents of the atmosphere as well as in other complex matrices, such as, petroleum and fossil fuel products, beverages, and fragrances.